Medical implant

ABSTRACT

Implant ( 1 ) for receiving the connecting bridge ( 17, 17′, 17 ″) of a medical device, comprising a longitudinal axis ( 9 ), a distal end ( 3 ) and a proximal end ( 4 ), whereby a receiving recess ( 10 ) for the connecting bridge ( 17, 17′, 17 ″) extends therefrom inside the implant ( 1 ), wherein the implant ( 1 ) can be connected on its outer surface area to the inner surface area of a receiving bore hole in a bone by force or adaptation, and whereby the connecting bridge ( 17, 17′, 17 ″), which is adapted to the receiving recess ( 10 ), can be anchored through clamping, shrinkage, adhesion or cementing. The anchored medical device rests on a contact surface ( 18 ) of the top ( 16 ) protruding radially outward in its cross-section beyond the cross-section of the receiving recess ( 10 ) on the proximal end ( 4 ) of the implant ( 1 ) across the entire surface against an allocated contact surface ( 5 ) of the implant ( 1 ) on its proximal end ( 4 ). In order to accomplish this the medical device can be easily assembled while simultaneously ensuring a high torsional safety as well as even force transmission between the implant and the medical device it is suggested that extending from the proximal end ( 4 ) of the implant ( 1 ) the receiving recess ( 10 ) contain a cylindrical section ( 10 Z), which is followed by a section ( 10 V) that is tapered in its cross-section, and that extending from the top ( 16 ) of the medical device the connecting bridge ( 17, 17′, 17 ″) also contain a cylindrical section ( 17 Z), which is followed by a section ( 17 V) that is tapered in its cross-section.

This application is a 371 of PCT/EP01/03948, filed on Apr. 6, 2001.

The invention concerns an implant which will house the connecting bridgeof a medical device and is composed of a longitudinal axis and a distaland proximal end, from which a receiving recess for the connectingbridge extends into the implant, making it possible for the implant tobe connected by force on its outer surface, or adapted to the innersurface of a receiving bore hole in the bone of a human or animal, inthat the connecting bridge, which is adapted to the receiving recess,can be anchored either by clamping, shrinking, adhesion or cementing,and once anchored, the medical device rests against the contact surfaceof the top which protrudes radially outward in its cross-section beyondthe cross-section of the receiving recess on the proximal end of theimplant, crossing the entire surface against an allocated contactsurface of the implant on its proximal end if at least in one section ofthe outer contour of the cross-section of the receiving recess is notcircular.

Such implant systems are, for example, widely known in dental medicine.In this case, the medical device to be received, will, e.g., be formedby a dental implant, cap or gingiva shaper. The implant is, for example,screwed into the jawbone.

An implant system of the above-described kind is known for example fromU.S. Pat. No. 5,961,328. The connecting bridge of the medical device andthe receiving recess of the implant are joined based on the key-lockprinciple, wherein a non-rotational joint is reached

With the help of locking elements protruding radially beyond theconnecting bridge, where these elements in the inserted state of themedical device mesh with the adapted recesses in the head portion of theimplant. Extending from the proximal end of the implant, the receivingrecess initially contains a conical section, which is followed by acylindrical section, the cross-section of which corresponds to thecross-section at the end of the conical section. The connecting bridgeof the medical device to be inserted into the receiving recess exhibitsa tapered shape in its cross-section in the direction of its distal end,whereby the outer contour of the connecting bridge is concave in thelongitudinal section and contains a saw-tooth surface structure. Thecross-section of the connecting bridge however is not circular, butrather in comparison to a rotationally symmetrical design a longitudinalstrip is missing on one side so that a plane section of the outersurface area is created, which runs parallel to the longitudinal axis ofthe connecting bridge.

The production of this familiar implant system is for one very complexand therefore expensive, and on the other hand the way the way forcesare introduced into the conical section following the head portion ofthe medical device is not optimal. Due to the tapered cross-section, theabsorption of forces, which arise especially with single-sided stress ofthe medical device and are directed lateral to the longitudinal axis ofthe connecting bridge, can possibly be limited, leading in the mostunfavorable case to tilt movements of the medical device.

The dental implant known from WO 99/29255 consists of a connectingbridge with a bottom portion, a central portion, an upper part and acrown slid onto the top. The dental implant is inserted in its entiretywith its conical bottom portion into an identical conical receiving borehole that has been adapted to it in an implant, which must first havebeen inserted into the jawbone and have healed sufficiently. Whenjoining the connecting bridge and the receiving bore hole, the principleof a clamping cone is applied. Although the possibility of torsion ofthe dental implant about the longitudinal axis of the connecting bridgeallows the angular position of the dental implant to be adapted exactlyin relation to a rotation about its vertical axis when inserted, it hasthe particular disadvantage that with greater stress, sufficient torsionsafety of the dental implant cannot be guaranteed for the implantsystem.

An alternative to the described implant system a screw connectionbetween the replacement tooth and the implant is the most widely usedtype of connection and is characterized by being easily reversible. Thedisadvantage here, however, is the large amount of time that is requiredfor screwing in the fastening screws—especially with a larger number ofdental implants—as well as the frequently unsatisfactory durability ofsuch a system. Due to the manufacturing process, no threads of the screwconnection ever exhibit the same wear behavior, which, in isolatedsections, results in elevated, and in other sections, reduced force ormoment transmission. This creates undefined stress conditions, which canresult in undesirable deformations and tension peaks. This in turn leadsto damage to the screw connection or to excessive stress on theconnection between the implant and bone, which in the worst case cancause a total loss of the implant.

The invention's purpose is to present an implant system, where theconnection between the medical device and the implant can be prepared ina simple manner, and the connection should also be characterized by theability to introduce even force across a large surface as along withtorsion safety.

Proceeding from an implant of the above-described kind, this task isresolved pursuant to the invention through the fact that the receivingrecess, extending from the proximal end of the implant, exhibits acylindrical section, which is followed by a section that is tapered inits cross-section, and that the connecting bridge, extending from thetop of the medical device, also contains a cylindrical section, which isfollowed by a section that is tapered in its cross-section.

The fact that contact with the contact surfaces occurs across the entiresurface causes force to be introduced evenly from the medical deviceinto the implant, avoiding tension peaks and thus excessive materialstress and damage, particularly as the cylindrical section of theconnecting bridge linked with the adapted cylindrical section of thereceiving recess affects safe fastening, where even an extreme lateralforce introduction into the medical device does not lead to tensileforce components in the interface between the medical device and theinner surface area of the implant. The implant pursuant to the inventiontherefore offers an especially high degree of safety against itdetaching and falling out, independent of the fact whether the medicaldevice is shrunk in, glued in or cemented in.

The non-circular cross-section, which can take on the form, for example,of a (rounded-off) polygon (triangle, square, pentagon, etc.) or anellipse or an oval or any random other such shape, prevents a torsion ofthe connecting bridge of the medical device about its longitudinal axis.The clearly defined angular position of the medical device in relationto its rotation about its vertical axis additionally eliminates thedifficult adjustment of the medical device's position during theinsertion process. The actual connection between the implant and theconnecting bridge occurs through clamping, shrinkage, adhesion orcementing.

Pursuant to one embodiment of the invention, the length of thecylindrical section of the connecting bridge, measured in the directionof the longitudinal axis of the implant, should be slightly smaller thanthe length of the cylindrical section of the receiving recess, alsomeasured in the direction of the longitudinal axis of the implant. Thisprovides a safe contact with the contact surfaces of the medical deviceon one hand and of the implant on the other hand, which is essential foran even application of forces across a large surface. The difference inlength should be such that, while taking the production tolerances ofthe individual elements into consideration, even in the most unfavorablecase, contact in the area of the contact surfaces is always ensured. Thedifference in length, however, should not be selected too high in orderto avoid unnecessarily large gaps between the connecting bridge and thereceiving recess in the area of the tapering cross-sections.

In a particularly preferred embodiment the contact surface is circularand runs in a plane vertical to the longitudinal axis of the implant.With the help of such a design, the efforts required during theproduction of the implant can be kept particularly low.

To avoid a pressure build-up that may impair the insertion motion duringinsertion of the connecting bridge into the receiving recess, betweenthe connecting bridge in its anchored state and the wall of thereceiving recess, at least one ventilation duct is included whichextends from a distal end face of the connecting bridge to the proximalend of the implant.

It is particularly beneficial when the contact surface of the implantcontains at least one ventilation groove which extends from aventilation duct to the surface area of the implant. Thus, a completelyunimpaired outflow of the air that is displaced by the connecting bridgeis guaranteed.

It is useful to size the connecting bridge in comparison to thereceiving bore hole such that the connecting bridge can always beinserted so far into the receiving recess that the contact surface ofits top rests across its entire surface against the contact surface ofthe implant.

One development of the invented implant consists of a design where thewall of the receiving recess contains a plurality of ring grooves, whichrun in the planes vertical to the longitudinal axis of the implant,respectively, or contains a helical groove. The ring grooves and/or thehelical groove ensure on one hand that the assembly process, especiallyin its last phase, is facilitated. Above all, it prevents stress of thesurfaces placed against each other and accomplishes better guidance ofthe connecting bridge. Additionally, when fixating the connecting bridgewith the help of adhesive, adhesive rings etc., in the ring groovesand/or in the helical groove a helical adhesive bead is created, viawhich axial forces can be absorbed.

Developing the invention further, it is suggested that the wall of thereceiving recess be equipped with at least one indentation, with whichan elastic clip element of a medical device, i.e. for example a cap, agingiva shaper, an impression rod and/or a temporary replacement toothcan positively engage. This way all components that have to be connectedonly temporarily with the implant can be inserted in a simple mannerinto the receiving recess and thus be

connected with the implant in an exactly predetermined position. Theclip element creates a positive connection that can be eliminated againby appropriate axial forces; for this purpose the clips are beneficiallyrounded off in order to enable non-damaging separation. During thetransitional period, the transmission of forces takes place via the endfaces. The time that is required for preparing the connection betweencomponents that are used only temporarily and the implant is drasticallyreduced, which expresses itself in a considerably gain in timeespecially for the simultaneous use of a plurality of implants.

In a preferred embodiment of the invented implant, the cross-section ofthe receiving recess takes on the shape of a rounded-off rectangle inthe vicinity of the proximal end of the implant and the shape of arounded-off square in the vicinity of its base, wherein the transitionbetween the above-mentioned cross-sectional shapes occurs smoothly. Itis useful when the shorter edge length of the rectangle corresponds tothe edge length of the square.

Pursuant to the invention, a medical device is suggested which has onecontact surface of a head portion protruding radially outward in itscross-section beyond the cross-section of the receiving recess on theproximal end of the implant resting across the entire surface against anallocated contact surface of the implant on its proximal end and wherethe outer contour of the cross-section of the receiving recess at leastin one section is not circular. This provides torsional safety in asimple manner and also enables greater moments of torsion to be absorbedwithout placing the connection at risk. It thus provides the opportunityof inserting the implant, e.g. together with a pre-assembled cap or agingiva shaper into the bone.

In a beneficial embodiment, the connecting bridge exhibits in thevicinity of its proximal end a cross-section in the shape of arectangle, the corners of which are rounded-off or broken more thanthose of the rectangle of the cross-section of the receiving recess inthe position that is allocated in the anchored state, and exhibits inthe vicinity of its distal end a cross-section in the shape of arounded-off square, the corners of which are rounded-off more than thoseof the square of the cross-section of the receiving recess in theposition that is allocated to the anchored state.

Furthermore it is suggested that the distal end of the connecting bridgeshould contain at least one axially protruding clip element, which inthe assembled state can be positively engaged with an indentation in thereceiving recess of the implant. The time required during assembly canthus be reduced considerably compared to screw connections and/ortemporary adhesive or cement connections.

The positive connection through the clip element can be eliminated in asimple manner if a section, which in the installed state is locatedoutside the receiving recess, contains in its surface area at least twoopposing indentations. In these indentations, hook-shaped contactelements of a tool shaped like tongs, can, for example, be inserted, toallow a clipped-on cap, a clipped-on gingiva shaper, impression rodand/or temporary replacement tooth to be easily removed again from theimplant by applying the appropriate axial forces.

Establishing a positive connection between the tool used to remove thecap, the gingiva shaper, the impression rod and/or the temporaryreplacement tooth can be simplified if the indentations form a ringgroove with a V-shaped cross-section.

Developing the invention further, a final replacement tooth can be suchthat the surface area of the connecting bridge contains a plurality ofring grooves which run in a plane vertical to the longitudinal axis ofthe connecting bridge, respectively, and in the anchored state of thereplacement tooth correspond to the ring grooves in the wall of thereceiving recess.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail in the following based on oneexample, which is shown in the drawing.

It shows:

FIG. 1 An implant with a clipped-on cap in a longitudinal sectionalview;

FIG. 2 Top view onto the cap;

FIG. 3 Top view onto the implant upon removal of the cap;

FIG. 4 Cross-sectional view along line IV—IV through the implantpursuant to FIG. 1;

FIG. 5 Cross-sectional view along line V—V through the implant pursuantto FIG. 1;

FIG. 6 Enlarged section of the engagement area of a clip element;

FIG. 7 Enlarged and diagrammatic section of the differing start of thecross-sectional taper of the implant and the connecting bridge;

FIG. 8 As in FIG. 1, however with clipped-on gingiva shaper;

FIG. 9 As in FIG. 8, however with a slot in the gingiva shaper fortransgingival healing;

FIG. 10 Blank for a temporary replacement tooth in a lab implant;

FIG. 11 As in FIG. 10, however of a finished temporary replacementtooth;

FIG. 12 As in FIG. 11, however in the implant pursuant to the invention;

FIG. 13 As in FIG. 10, however of a final replacement tooth;

FIG. 14 As in FIG. 11, however of a final replacement tooth;

FIG. 15 As in FIG. 12, however of a final replacement tooth, and

FIG. 16 As in FIG. 15, however with a connecting bridge with ringgrooves in the surface area.

FIGS. 1 through 5 reveal an implant 1 consisting of titanium, which hasa roughly conical outer base shape and on its outer surface areacontains an outer thread 2. Implant 1 contains a rounded-off distal end3 and a proximal end 4, which is formed by a largely circular contactsurface 5. In a section 6 following the contact surface 5, the implantexhibits on its outside a cylindrical shape with a high-polished surfacearea 7. In a thread area 8 that follows the implant 1 has a conicaldesign. Starting from the contact surface 5, parallel to thelongitudinal axis 9 of the implant 1, a receiving recess 10 extends,which runs across the entire length of the section 6 as well as aportion of the length of the threaded section 8.

The diagrammatic depiction pursuant to FIG. 7 shows that extending fromthe proximal end 4 of the implant 1 the receiving recess 10 firstcontains a cylindrical section 10Z, which is followed by a section 10Vthat is tapered in its cross-section. Adapted to this feature, extendingfrom the head portion 16, the connecting bridge 17 of a replacementtooth to be inserted initially also exhibits a cylindrical section 17Z,the diameter of which is slightly smaller than the diameter of thereceiving recess 10 in its cylindrical section 10Z. The cylindricalsection 17Z of the connecting bridge 17 is followed by a section 17V,which is tapered in its cross-section. Since the length 6 a of thecylindrical section 17Z of the connecting bridge 17 is dimensionedslightly less than the length 6 b of the cylindrical section 10Z of thereceiving recess 10, it is impossible for the connecting bridge 17 torest against the wall 12 of the receiving recess 10 in the area of thetapering sections 10V, 17V. This kind of adaptation of the componentsrather ensures that the contact surfaces 5 and 18 always rest thereacross their entire surface at the proximal end of the implant 1. Thedifference between the lengths 6 b and 6 a, i.e. the axial distancebetween the peripheral edges 12 a on the connecting bridge 17 and 12 bon the receiving recess 10 of the implant 1, is dimensioned such thateven in the most unfavorable case of production tolerances always aminimum gap is maintained in the sections 10V and 17V. The difference inlength should otherwise be kept as small as possible in order to keepthe gap in the area of the tapering sections 10V and 17V small.

As FIGS. 3 and 7 show, the cross-section of the receiving recess 10takes on the shape of a rounded-off rectangle in the area of thecylindrical section 10Z. Starting with the threaded area 8, thecross-section of the receiving recess 10 tapers continuously in asubsequent section 10V so that on the base 11 of the receiving recess 10the cross-section has the shape of a rounded-off square (see FIG. 5). Inthe threaded area 8, the transition from the rounded-off rectangular tothe rounded-off square cross-sectional shape occurs continuously andsmoothly.

As particularly shown in FIG. 1, the wall 12 of the receiving recess 10contains a plurality of ring grooves 13, which are aligned vertical tothe longitudinal axis 9. Furthermore the wall 12 is equipped with anupper and a lower clip groove 14 o and 14 u, the function of which isexplained below based on FIG. 6.

Implant 1 depicted in FIG. 1 is inserted in a cap 15, consisting of aroughly cylindrical head portion 16 and a coaxially thereto alignedconnecting bridge 17, which extends in the receiving recess 10. Acontact surface 18 of the head portion 16 rests positively on thecontact surface 5 of the implant 1.

As FIG. 3 reveals, the connecting bridge 17 has in its upper section aroughly rectangular cross-section, wherein the corner areas are brokenin such a way that in the rounded-off areas of the cross-section of thereceiving recess 10 between the connecting bridge 17 and the wall 12 ofthe receiving recess 10 four ventilation ducts 19 a are formed. Airdisplaced when inserting the connecting bridge 17 in the receivingrecess 10 can thus flow out upward without causing a pressure build-upthat would impair the assembly process, wherein the air can escape tothe outside through four radially outward extending ventilation grooves19 b, which are incorporated in the end face 5 of the implant andcommunicate with the ventilation ducts 19 a.

Since the cap remains on the implant 1 only temporarily afterimplantation, it is connected with implant 1 only through four clipelements 20, which engage with the clip groove 14 o. Instead of theengagement of the clip elements 20 in the upper clip groove 14 o shownin FIG. 1, engagement in the lower clip groove 14 u is also possiblewith an appropriately extended connecting bridge 17.

Cap 15 is already inserted into implant 1 by the implant manufacturerand upon preparation of an appropriate bore in the bone serves thepurpose of screwing implant 1 in with the help of a screwdriver, whichengages with the slot 21 shown in FIG. 2. Due to the roughly rectangularcross-section of the connecting bridge 17 and the adapted receivingrecess 10, the introduction of moments of torsion into the implant 1 ispossible via the cap 15. Upon implantation, the cap 15 remains on theimplant 1 in order to protect also the receiving recess 10 from outsidecontamination.

Approximately three to six months after insertion of the implant in thejaw bone, the healing process will be completed far enough to be able toopen up the mucous membrane covering Cap 15 in a second surgery. Cap 15is removed, which is accomplished by reaching into a V-shaped ringgroove 22 in the head portion 16 with the help of a tool in the shape oftongs and removing the entire cap 15 upward from the implant 1 with aslight jerk in the axial direction. Into the receiving recess 10 of theimplant 1 now a connecting bridge 17 of a gingiva shaper 23 is inserted,as shown in FIG. 8. The fastening principle is the same as with the cap15. As an example, FIG. 8 shows that the clip elements 20 of the gingivashaper 23 snap into the lower ring groove 14 u. Similarly feasiblehowever is a gingiva shaper 23, where the clip elements engage with theupper ring groove 14 o.

FIG. 9 shows a gingiva shaper with a slot, which is employed fortransgingival healing of the implant.

FIG. 10 depicts a lab implant 1L, into which a blank 24 of a temporaryreplacement tooth has been inserted, also with the help of a connectingbridge 17. The blank 24 is truncated and expands, starting from the endface 5L of the lab implant 1L, at an angle α of 15°. This way, slantedpositions of the implant 1 or 1L in relation to adjacent teeth can becompensated for in wide angular ranges in all directions. The connectingbridge 17 of the blank 24 also contains clip elements 20, which ensureuncomplicated fixation and removal of the blank 24.

FIG. 11 shows a finished temporary replacement tooth 25, which wasprepared by cutting the blank 24 in a dental laboratory. Onto the groundblank an outer ceramic layer 26 has been burned.

The finished temporary replacement tooth 25 can subsequently be insertedon the patient in the implant 1 and be fixated there with the help ofthe clip elements 20 until the patient can be provided with the finalreplacement tooth 28 (FIG. 12).

Like the temporary replacement tooth 25, this final replacement tooth 28is produced from a blank 27 that is truncated in its head portion (FIG.13), permitting a correction to slanted position in all directions inwide angular ranges. The connecting bridge 17′ of the final replacementtooth 28 and/or its blank 27 do not contain any clip elements, but—apartfrom the rounded-off areas—it is adapted to the cross-sectional shape ofthe receiving recess 10 across the entire length of the connectingbridge 17′. Due to the ring grooves 13 in the wall 12 of the receivingrecess 10, the connecting bridge 17 can be inserted without difficultyuntil the end face of the head portion of the blank 27 rests against theend face 5L of the lab implant 1L. Different starting areas of the“conical feature” ensure a non-positive connection via the contactsurfaces 5 and 18 (see also FIG. 7). Proceeding from this installationposition of the blank 27 in the lab implant 1L, the final shape of thereplacement tooth 28, which in turn contains a ceramic layer 26 that hasbeen burned on, can be prepared (FIG. 11).

The completion of this process consists of removing the finalreplacement tooth 28 from the lab implant 1L and inserting it into theimplant 1 located in the jaw bone. In the assembled state, the twocontact surfaces 5 and 18 rest non-positively against each other. Anon-positive connection, which is formed with the help of adhesive orcement or is formed by clamping forces in the case of a shrinkageconnection, exists also between the outer surface areas of theconnecting bridge 17 and the wall 12 of the receiving recess 10.

Pursuant to FIG. 15, the surface area 29 of the connecting bridge 17′and the contact surface 18 of the head portion are coated with asuitable adhesive or cement, which fills in the ring grooves 13 in thereceiving recess 10 basically completely when inserting the connectingbridge 17′. After curing the adhesive, adhesive beads are thus created,which adhere to the connecting bridge 17′ and establish a positiveconnection with the implant 1. Another positive connection exists viathe contact surfaces 5 and 18, wherein the adhesive in this area ispreferably applied in such a thin layer that only the surface roughnessof the contact surfaces is filled in and there is still material contactbetween the adhesive and the implant/replacement tooth. Either way,adhesive should not protrude on the sides of the contact surfaces 5 and18.

The stability of the connection between the replacement tooth 28 and theimplant 1 can be further improved, even if in the surface area of theconnecting bridge 17′ a plurality of ring grooves 13″ is incorporated,which correspond to the ring grooves 13 in the wall 12 of the receivingrecess 10. Such a design is shown in FIG. 16. Here, adhesive rings,which are circular or oval in their cross-section, are formed, whichestablish a positive connection between the replacement tooth 28 and theimplant 1.

1. Implant for receiving a connecting bridge of a medical devicecontaining a head portion, comprising a longitudinal axis, a distal end,a proximal end and a top portion having a contact surface, whereby areceiving recess for the connecting bridge extends therefrom intoimplant, wherein the implant can be connected by its outer surface areato the inner surface area of a receiving bore hole in the bone of ahuman or animal body by force or adaptation, whereby the connectingbridge, which is adapted to the receiving recess, can be anchoredthrough clamping, shrinkage, adhesion or cementing, wherein in theanchored medical device rests in contact with the contact surface of thetop portion protruding radially outward in its cross-section beyond thecross-section of the receiving recess on the proximal end of the implantacross the entire surface against an allocated contact surface of theimplant on its proximal end and the outer contour of the cross-sectionof the receiving recess at least in one section is not circular, whereinextending from the proximal end of the implant the receiving recesscontains a cylindrical section, which is followed by a section that istapered in its cross-section, and that extending from the head portionof the medical device the connecting bridge also contains a cylindricalsection, which is followed by a section that is tapered in itscross-section; and wherein said implant in its anchored state betweenthe connecting bridge and the wall of the receiving recess at least oneventilation duct is formed, which extends from a distal end face of theconnecting bridge to the proximal end of the implant; and wherein forthe contact surface of said implant at least one ventilation groove isincorporated, which extends from a ventilation duct to the surface areaof the implant.
 2. Implant pursuant to claim 1, wherein measured in thedirection of the longitudinal axis of the implant the length of thecylindrical section of the connecting bridge is slightly less than thelength of the cylindrical section of the receiving recess, also measuredin the direction of the longitudinal axis of the implant.
 3. Implantpursuant to claim 1, wherein the contact surface is circular and runs ina plane vertical to the longitudinal axis of the implant.
 4. Implantpursuant to claim 1, wherein the wall of the receiving recess isequipped with a plurality of ring grooves, which each run in planesvertical to the longitudinal axis of the implant, or with a helicalgroove.
 5. Implant pursuant to claim 1, wherein the wall of thereceiving recess is equipped with at least one indentation, with whichan elastic clip element of a medical device can positively engage. 6.Implant pursuant to claim 1, which is provided to receive a replacementtooth.
 7. Implant for receiving a connecting bridge of a medical devicecontaining a head portion, comprising a longitudinal axis, a distal end,proximal end and a top portion having a context surface, whereby areceiving recess for the connecting bridge extends therefrom intoimplant, wherein the implant can be connected by its outer surface areato the inner surface area of a receiving bore hole in the bone of ahuman or animal body by force or adaptation, whereby the connectingbridge, which is adapted to the receiving recess, can be anchoredthrough clamping, shrinkage, adhesion or cementing, wherein in theanchored medical device rests in contact with the contact surface of thetop portion protruding radially outward in its cross-section beyond thecross-section of the contact surface of the implant on its proximal endand the outer contour of the cross-section of the receiving recess atleast in one section is not circular, wherein extending from theproximal end of the implant the receiving recess contains a cylindricalsection, which is followed by a section that is tapered in itscross-section, and that extending from the head portion of the medicaldevice the connecting bridge also contains a cylindrical section, whichis followed by a section that is tapered in its cross-section; andwherein the vicinity of the proximal end of the implant thecross-section of the receiving recess takes on the shape of arounded-off rectangle and in the vicinity of the its base it takes onthe shape of a rounded-off square, wherein the transition between theabove-described cross-sectional shapes is smooth.
 8. Implant pursuant toclaim 7, wherein a shorter edge length of the rectangle corresponds toan edge length of the square.
 9. Medical device, which is received bythe receiving recess of an implant, said receiving recess containing awall, wherein said medical device rests on the contact surface of a headportion protruding radially outward in its cross-section beyond thecross-section of the receiving recess on the proximal end of the implantacross the entire surface against an allocated contact surface of theimplant on its proximal end, that the outer contour of the cross-sectionof the connecting bridge at least in one section is not circular, andthat extending from a head portion the connecting bridge has acylindrical section, which is followed by a section that is tapered inits cross-section; and wherein the vicinity of its proximal end theconnecting bridge has a cross-section in the shape of a rectangle, thecorners of which are rounded off or broken more than those of therectangle of the cross-section of the receiving recess at the positionallocated in the installed state, and that in the vicinity of its distalend it has a cross-section in the shape of a square, the corners ofwhich are rounded off or broken more than those of the square of thecross-section of the receiving recess at the position allocated in theinstalled state.
 10. Medical device pursuant to claim 9, wherein thedistal end of the connecting bridge contains at least one axiallyprotruding clip element, which in the assembled state can positivelyengage with an indentation in the receiving recess of an implant. 11.Medical device pursuant to claim 10, wherein a section, which in theassembled state is located outside the receiving recess, is equipped onits surface area with at least two opposing indentations.
 12. Medicaldevice pursuant to claim 11, wherein the indentations form a ring groovewith a V-shaped cross-section.
 13. Medical device pursuant to claim 9,which is a cap, a gingiva shaper, an impression rod and/or a replacementtooth.
 14. Replacement tooth pursuant to claim 13, wherein the surfacearea of the connecting bridge is equipped with a plurality of ringgrooves, which each run in a plane vertical to the longitudinal axis ofthe connecting bridge and in the anchored state of the replacement toothcorrespond to the ring grooves in the wall of the receiving recess.